text:
How low can a helicopter fly above a residence if the helicopter is an air ambulance landing?
Two medical helicopters just located directly across the street from my home.  Their landing pad is less than 500 feet from my property.  When they land, the helicopter is only 100 to 200 feet above my roof and is causing stress cracks in my home. The noise and the fact that the downward wind from rotors is causing vibration in my walls. The pilots have many other options for directions to approach and land but use the shortest route.
What are my rights? Don't I have the right to quiet and peaceful use of my home?
After all, those helicopters are part of a business and I was here 10 years before they located in this unzoned area of Alabama.

This document appears to contain the relevant regulations, but I'm not sure I can find a definite answer. There are useful diagrams on PDF page 110 about the approach/landing path https://www.faa.gov/documentlibrary/media/advisory_circular/150-5390-2b/150_5390_2b_part3.pdf

You mention "unzoned area of Alabama". If there really are no zoning ordinances in your area there is, unfortunately, probably very little you can do. However, if there really is no zoning, there's nothing to stop you from erecting a couple of 199 foot towers* in your back yard and stringing some wires between them. You'll want to paint them brightly, of course, and put some of those nice, orange pilot-warning balls on the wires because you don't want to kill anyone.

*I say 199 feet because once you hit 200 feet, you're required to have anti-collision lighting on the towers, and you probably don't want to pay for the electricity or have them shining in your windows all night long.

How about calling the air ambulance company and talking to them first? Explain what you've explained here and ask if they can alter their approach.

How low can a helicopter fly when it is landing? All the way down to the ground, I hope. Otherwise it's not much of a landing.

Related: What is the minimum allowed altitude for helicopters over a residential area in the US?

"What at my rights?" This is more a question for Law.SE. We can answer according to the FAA, but they don't address your rights as a homeowner.

Related

What Carey Gregory said. New facilities often make an open house day around their start up, the neighbourhood usually appreciate such things. Maybe a good opportunity to talk to each other? Or just walk over when you have time. Are Stress cracks by low flying helicopters usual?

I’d venture a guess that this is covered under Good Samaritan Laws and, unless the helos are operating within about three rotor diameters from your property any effect of rotor downwash are going to be comparable to a firm breeze.  Finally these things are being used in legitimate and infrequent emergencies to save someone’s life and it does take a real jerk to put their brief inconveniences over a critical lifesaving operation.

Talk to a lawyer.
Disclaimer: I am not a lawyer, and this is not legal advice.
The fact of the matter is, regardless of whether or not they've got FAA clearance to operate the way they do, they're causing physical damage to your property. As such, I would recommend talking to a lawyer about what your legal options are. While suing them for damages would definitely be a step you could take, a lawyer would be able to advise you on how best to navigate the process leading up to that, potentially involving things like Cease and Desist letters or negotiated settlements with the company in question.
Since you're from America, it's also entirely possible that your state might simply seize your house with Eminent Domain and give you a token payment for its "fair market value", since the construction and operation of a hospital with medical helicopters clearly falls within its remit. As a result, I would recommend to be prepared to start looking for a new house should you begin a dispute with them.

Helicopters alike other aircraft are allowed to be as low as they need to be upon landing or takeoff. Height minimums however exist too for normal flight. The approach they are taking could be the published approach for that heli-pad as well.

For completion of your answer, it would be nice to illustrate with figure taken from a specific example (e.g. taking one helipad in urban area)

@ManuH Aircraft at least in Canada have over flight minimums for a few things. Flight over a dense area of buildings such as a city require 1000’ of vertical distance where as a group of buildings such as a village, camp ground or a gathering of people require 500’ of vertical distance. The horizontal distance from any object is 500’ so that means from a tower or landing near a house. Aircraft are allowed to be as low as they need to be during landing and takeoff as required and depending on the approach procedures for helicopters to that specific pad.


text:
What's the rattling noise on an A320?
I recently flew on an A320, and during takeoff when the aircraft was rotating, I heard a loud rattling noise. If I had to guess I would say it came from the gear below but I can't be sure. I was sitting slightly behind the wings. The noise stopped when we lifted off the runway.
Edit: The noise sounded a bit like a stick shaker, a loud vibration.

Does this answer your question? What is this sound from Airbus aircraft before take off?

@Pondlife I'm not so sure about the duplicate. The PTU has more of a barking sound, not a rattling. It should also not activate during rotation since there shouldn't be any pressure difference between the yellow and green systems at that time.

Maybe the runway just wasn't even?

Definitely not the barking PTU sound, I heard that one too during engine startup but this was different. Sounded too rough to be the runway, but I guess that's a possibility.

@Bianfable I'm not sure either, but it seemed at least somewhat possible. This is why we (mostly) need multiple votes to close; it's completely possible that I'm wrong

Rattling that disappears after liftoff is normally associated with a vibrating tire transmitting vibrations up through the airframe, and causing some sort of interior panel that is a bit loose to rattle in sympathy.  On most airliners the brake system applies the main wheel brakes momentarily, once weight-off-wheels, to prevent the usual spin down vibrations during retraction (Nosewheels normally use a friction brake that contacts the tire when it's fully up for the same purpose).  So if the wheel is shaking and making other things shake it will stop as soon as you're airborne.
Airliner wheel assemblies are usually statically balanced vertically like motorcycle tires, not dynamically balanced on machines like car tires (I shudder to think of the cost of a dynamic balancer that can do wheels that big).  You can have a vibration mode that comes in at a certain tire RPM, so all of a sudden starts to shake, then you lift off and the brakes are tapped by the braking system to stop the  wheels, and the vibration stops.

source: Stack Exchange

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

sort: votes


text:
Can a private jet take off without notifying anybody and land on private land in another country?
If you have a friend in the USA who owns a lot of land that is suitable for landing a plane, and you own a private jet with 2 pilots in Norway, can you take off in private property without notifying anybody on what you have on the plane and where you are going or anything like that and fly to the USA and land on the property of your friend? Is that legal to do?

Does this answer your question? What stops an international private airplane from landing outside of airports with a customs zone?

It would amaze me if the USA (or any country) was okay with airplanes of any origin enter its airspace without being at least notified. (But I'm no pilot, so maybe that's not as unordinary as I think)

oddly specific...

Is your "friend" in the CIA (a service of the USA government), and is "Norway" an alternative word for "Nicaragua"?

@BruceWayne I'd imagine a set of fighters getting scrambled to the location of the airplane if no contact can be made and for the plane to be forced down if still not responsive.

"But would anybody notice that im transfering gold if the gold is hidden and i put the gold there long before the acctualy travel. And would i need to arrange customs to come to me? And how would i do that. This is just me wondering if this is acctualy possible-" - Transferring gold from Norway to the US without speaking to Customs seems ill advised

@IronEagle - asking for friend...

You really should change the title to match the question.  In the US, it's perfectly possible to take off and land without notifying anyone, it's crossing borders without going through customs & immigration that's the problem.  Doesn't really matter if you're flying a private jet, or climbing over Trump's wall.

If you declare Mayday I guess nothing stops you from landing anywhere?

@ViktorMellgren Except all the questions about the supposed emergency...

@OskarSkog That's after the landing, it doesn't stop the landing itself :-)

@Mast: Obviously, if your engine quits, you're going to land pretty soon.  If you're lucky, you might even have an airport or flat field within gliding distance :-)  But you can bet that emergency responders, law enforcement, and accident investigators will show up and ask questions.

You may want to read about Mickey Munday.

Yes, it is possible to land an airplane in the US at a private airport when you have taken off from a foreign airport.
No, you may not do it legally.
Doing this is a federal crime. Since you are smuggling something, you may not care about the legality. When you are eventually caught, you will go to prison. Your assets will be confiscated by and forfeited to the government. And once you are released from prison, you will be deported and blacklisted from entering the US ever again. Your gold will not be returned to you.
It is not worth the risk. Especially when the gold is worthless unless you can convert it to money. You can’t do that legally either (more prison time). Even money gotten through illegal means is forfeited to the government.
No matter from where you takeoff, nor in what country your aircraft is registered, if you cross the US Air Defense Identification Zone, you have to land at an Airport of Entry before proceeding elsewhere. You have to declare any goods or monetary instruments (even gold) you are transporting to Customs and Border Protection located at the AOE. There are trade laws, aviation laws, customs laws, banking laws, tax laws, Anti-terrorist laws, etc. that you will be violating if you do not.

+1 for the phrase "the gold is worthless" alone.

I don't see anything about gold in the question?

yeah but what if you can swap the gold for the money and refuel the plane and fly away again before the FBI come and arrest you?!

Ctrl+F "gold" Enter... oh look, comments by the OP!

What is it about ILLEGAL that you don’t understand? There is no legal way to convert the gold into money. Any attempt to do it will create a paper trail. You will then be arrested in any country that has an extradition treaty. Any illegal means of converting the gold will cost you a huge vig and possibly your life. Why would a criminal not kill you and take your gold and your plane. You would be playing Russian Roulette with your only reward for the risk factor being the tax savings that would be less than the vig.

Re "Since you are smuggling something..." the irony is that you can bring in as much gold as you want, perfectly legally, without paying taxes or customs duties.  The illegality is not going through customs.

@jamesqf - You are partially right. Gold for personal possession would be fine up to some limits. CBP requires you to declare large dollar amounts of items you purchase outside of the US. They also require you to declare any items you are bringing in to the US to sell, create a business or trade, or for commerce. In most cases, they will not make you pay tax or tariffs on those goods. I assume the OP is talking about way more than that amount. I was once stopped both upon leaving the US and upon entering another country because of the amount of shoes I was carrying. Donations for an orphanage.

The only reason anyone would want to do something like what the OP is proposing is if the item, in this case gold, was itself illegal. For instance nazi gold, blood diamonds, Krugerrands, Chinese firearms, stolen artwork, illicit drugs. All items that people have tried to smuggle into the US. These people have ended up in federal prison. Nuff said?

that's it! the non extradition treaty country is the key! right then, now I can change step two of my plan from "????" to: 1. fly the gold to the US; 2. escape to a non extradition treaty country; 3. PROFIT! Thanks DeanF - that's a foolproof plan if ever I saw one!

Lol. Well, many fools have proven the system works. Our prisons are full of them. Maybe StackExchange can start a criminal endeavors site. All the usual suspects in one place.

Just for the record, it's extremely easy to convert gold to cash, in reasonable amounts, with no paper trail.

Key word is reasonable. I don’t think reasonable would be the amount that would warrant the risk of smuggling on a transatlantic flight. You are right, though.

@Dean F.: Re "The only reason...", that's simply not part of the question.  Maybe the person doing this simply does not know, as the OP apparently didn't, that it's perfectly legal to bring in as much gold as you want.  WRT ending up in federal prison, you're only counting the ones who got caught.  We have no way of knowing how many succeeded - except that quite obviously drugs are successfully smuggled in large quantities.

Ignorance of the law would not be a defense for the OP. Blatant disregard of the law by others is just that, a blatant disregard. As my previous answer has stated. It is extremely possible. It happens all the time amongst the criminal minded. As a reminder, it takes both skill and luck. There are many who ran out of one or both. The risk versus reward don’t add up in the case of legitimate reasons. That only leaves the criminal (blatant disregard is still criminal) and the ignorant. Both are still illegal.

@DeanF. Regarding the criminal endeavours site, Silk Road mastermind “Dread Pirate Roberts" might say it'd be a bad idea.

@AndrewMorton Of course, nobody knew that was him until they actually caught him. Then they could link him to that SO account. It probably helped slightly as evidence too ("see, this guy has a history of doing stuff with Tor, so there's a better chance we've got the right person")

Does entry within the ADIZ require you to land at a US airport? I thought it just required identification.

No, you would need to arrange for customs as you are crossing an international border.

But would anybody notice that im transfering gold if the gold is hidden and i put the gold there long before the acctualy travel. And would i need to arrange customs to come to me? And how would i do that. This is just me wondering if this is acctualy possible

@LineGolem This is a really bad place to ask how to commit a crime.  Smuggling is a felony in almost every country -- will result in confiscation of the jet and everything aboard, even if it never goes to trial.  It's a very, very bad idea.

Hey! I was thinking that, im just verry curious of this because of everything i see on TV and in the News i understand smuggling is a felony and doing it is really a bad thing, im just wondering on about how these kind of things work! And i really dont know where i should or who i should ask if im wondering about things like this. I try to see things that would be hard to do and for sure probably almost stupid to try, and see if i would be able to find an solution, im sorry if this is the wrong place to ask around i will take it down right away if thats better, anyways thank you for respoindin

@LineGolem That won't work at all. You'll have to declare all the gold to Customs when you land.  You can also expect a swift rap on the knuckles for not landing at an international airport to clear Customs then going on to your destination.

@Zeiss Ikon: AFAIK (and per Google, but I am not a lawyer), there's no legal problem with bringing in as much gold as you want, as long as you declare it: https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&cad=rja&uact=8&ved=2ahUKEwjX7-jlouTnAhUTnZ4KHdepBlkQFjABegQIDBAF&url=https%3A%2F%2Fwww.specialtymetals.com%2Fblog%2F2018%2F12%2F13%2Fcan-you-carry-gold-coins-and-bullion-into-the-us&usg=AOvVaw0HfWtiJbUTXJRKbkqFQn7G  If it's an unreasonably large amount, you might have various law enforcement agencies snooping around to find out whether you acquired it legally, though.

@LineGolem It might be better to ask first about what the normal process is for crossing a border in a private plane. This may answer all your questions by itself.

@LineGolem : if you have so much gold, then you can afford to hire a good lawyer, who will provide a much better legal solution than random strangers on the Internet.

@everyone Could we stop assuming criminal intent and just focus on answering a perfectly valid and interesting question?

@jamesqf AFAIK, in theory it's legal, but in practice it is a good way to get your gold confiscated (stolen) by the government. They will say that the gold is probably the proceeds of a crime, because non-criminals don't normally carry around large amounts of gold. To get it back, you will have to prove that it did not come from a crime (by proving where it did come from). Look up "civil asset forfeiture in the USA"

@user253751: As I said, questions might be asked.  As for confiscation, I've never had enough gold (nor the private jet) to make a practical experiment.  I suppose I could try it by flying a couple of gold coins to Canada and back in the Piper...

In general*, any time people or cargo enter another country, they must do so at a designated Port of Entry, i.e. where customs and immigration officers are stationed. This is true regardless of whether traveling by land, sea or air. Trying to enter other than at a PoE is usually a serious crime, and in the case of flying without a proper flight plan, may even get you shot down.
In the US specifically, you can request (for a fee) that these officers meet your flight at an airport other than a designated PoE, which is a really convenient perk for GA pilots. As far as I know, they will only agree to do this at public airports, and if you ask about a private airport such as your friend's farm, they'll tell you to land at a public airport first to legally enter the country and then continue to the private one as a domestic flight.
(* Open border agreements like Schengen are an obvious exception.)

Think about how your question is fundamentally different from this one:

If you have friend in the USA that owns a lot of land that is suitable for landing a plane, and you own a private jet with 2 pilots in Colombia, can you takeoff in private property without notifying anybody on what you have on the plane and where you are going or anything like that and fly to USA and land on the property of your friend? Is that legal to do?
But would anybody notice that I'm transferring cocaine if the cocaine is hidden and I put the cocaine there long before the actual travel. And would I need to arrange customs to come to me? And how would I do that. This is just me wondering if this is actually possible.

I'll bet you can answer this question all by yourself without even consulting additional sources.  If not, you can probably put on your Customs and Border Patrol hat and ask yourself: "What would I think of a covert flight of this nature crossing into my airspace?  It's probably a totally cool, totally legal flight with no contraband on board.  I'm gonna go ahead and do nothing."

You forgot the part about filing an international flight plan not terminating at a port of entry.

There's a large number of problems with this plan that are well-covered by the other answers.  I was just trying to illustrate that the OP probably didn't need any expert advice at all to answer this question.

I totally agree with you.  My comment was in jest because the OP actually asked whether filing a flight plan might alleviate any problems!

you've hit upon the solution! if OP wears their CBP hat, then the people at customs will think he works there, and then they won't even look for the gold! (this is the best question of any SE site of the decade so far!)

@MichaelHall: Why do you need to file a flight plan at all if you're VFR the whole way?

@Joshua, you don't need to.  You aren't "getting" my comment in the context I used it...  It was not a recommendation to file, it was a comment about the ignorance of the OP in thinking that filing might help him achieve the goal, vs lead the authorities straight to him.

No, your plan could never succeed.  You could not file a legal flight plan since your plan has no provision for landing at an appropriate port of entry for customs and immigration clearance.  If you attempt to make the flight without filing a flight plan, you would necessarily need to transit the North American ADIZ (Air Defense Identification Zone).
The map below does not show the Alaska zone, but rest assured it also exists - there is no way to cross into the north american land mass without being detected.

Any aircraft flying in these zones without authorization may be identified as a threat and treated as an enemy aircraft, potentially leading to interception by fighter aircraft.

With no defensible justification for your presence in that airspace you would be treated as a hostile aircraft and dealt with as such.
Image Credit.

I'm certain there will be problems with this, because this is very much the way smugglers move goods across a border without letting customs authorities inspect it.
If you cross from international airspace to American, without a flight plan, at the very least you'll be directed to land at a recognized airport for customs, and if you don't respond to attempts at contact, it's possible warplanes might be dispatched to intercept you -- this could even go as far as a shoot-down, in the worst case.
Even if you "aren't smuggling," if you have anything of value on board, this kind of flight is smuggling.  It will also run afoul of immigration laws, if anyone on board isn't an American citizen (and will be seen as suspicious in that regard even they are).

Comments are not for extended discussion; this conversation has been moved to chat.

all_licenses: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/


text:
3-D Printed Carbon Fiber UAV Skin
aviation pros!
New to the aviation/RC world and would like to ask a serious question about using composites for the skin of a UAV I am developing my first time out.
Want to use carbon fiber for a planned UAV approx 6-8 feet in length and weighing in at about 200 lbs powered by electric motors.  But, instead of making a carbon fiber skin from a stryofoam (or similar) mold, I am thinking of printing out the skin (using a carbon fiber filament) from a large format 3-D printer as separate panels up to 20" x 20".  They would then be attached to the UAV's metal airframe (of a semimonocoque style).
It just seems like a much simpler way than molding the skin from a plug.  Yes, I am concerned about the necessary strength and elasticity needed from the skin but I am hoping that a well thoughtout design for the panels (and especially for the nose and empennage) along with a CF/nylon filament will provide that.  I have also considered the production time and filament costs associated with this method, but it just seems so darn simple and easy.
But what do the pros think.
Thanks.

"Carbon fiber filament" for Fused Deposition Modelling (FDM) printers doesn't have the properties you believe it does.  While perhaps a little stronger than a plain filament, in comparison to traditional items made of carbon fiber it is actually quite brittle and easily snapped, because the fibers are all chopped up into short pieces and mixed with the plastic resin.
To build something useful for an aircraft, you need fibers of meaningful unbroken length - either large pieces of cloth, or to run a continuous filament back and forth many times.
There have been thoughts of making FDM printers which would place a continuous carbon filament along with a thermoplastic "printer filament" as a binder, but that's not what a roll of "carbon fiber printer filament" gets you.  Also note that even a filament-stringing machine would only make structures which were strong in the plane the layers, but not against delamination between layers; to get a strong 3d shape like an aircraft panel, you would need a six axis machine which built in a way sensible for the shape of the component being built.
You could potentially use some ordinary or soluble filament to print a mold for conventional carbon fiber layup.

Wonderful answer!  Part of what you wrote I was aware of--that aircraft skin requires longer fibers than the particles of fiber in filaments.  But I thought that maybe by thicken the panels it might compensate for the weakness inherent in filament fibers.  And someone on YouTube had that problem of brittleness when trying to print an AR-15 lower receiver even w/ 85/15 CF to nylon.  However, I was toying w/ the idea of using the printed panels assembled together as a complete fuselage to use as a plug for a CF mold. I'm glad to hear that's possible.  Any more thoughts on doing that?

@VSSDefense: Short fibers will have random orientation while long, unbroken fibers will be oriented along the direction of maximum load. Much of the chopped-up fibers will not contribute to the desired strength because they have the wrong orientation.


text:
Why is YF22 designed with conventional rudders while YF23 with all-moving rudders?
Are all-moving rudders more stealthy? If so, how come YF22 which is just as fixated with rear body stealthiness as the YF23 comes with conventional ones?
Also, all-moving rudders have fixed camber, which means they are far more efficient during supersonic flight, right? Another reason for an all-moving design.

As a general rule when you see an all-moving surface vs a fixed fin and control surface it's because you get more control authority per unit of surface area, so the surface itself can be smaller.  Better stealth, less drag.  You lose the passive weathervaning effect that provides basic yaw stability you get with a fixed fin, but with a fully active artificial stability system, that might be acceptable to the designer (although maybe not to the Air Force).
The 23 went with what amounts to a V tail, on top of all-moving surfaces, with the surfaces providing yaw and pitch authority at same time, and a fully active artificial stability system to make up for the lack of fixed surfaces.  This would have had much less drag than the regular horizontal and vertical surfaces, and probably a better radar signature to boot.
Why it lost out to the 22? According to Wikipedia, it was faster and had better stealth, as your would expect from the tail arrangement, but was less agile, so we know what the Air Force's priorities were. And there was probably a range of other factors that made the 22 a better choice overall (it could be that the 23 was just a bit too radical, which may have impacted maintainability, reliability, and cost factors in a way that made the 22 look like a safer bet).

Sure, but why LM decided to go with a conventional rudder? the f22 relies on a computer to be flyable and has all moving elevators anyway.

Maybe they decided they wanted the passive yaw stability of a fixed fin.  You see very few all moving rudders.  The only other ones that spring to mind is the SR71 and the Zenith homebuilts although I'm sure there are others.

@JohnK the Sukhoi PAK FA also has all moving rudders; however, the Russians weren't too concerned about stealth. All the hype about it being more maneuverable than the F-22 goes to the wayside when you consider that it's more a turn-fighter with stealth as an afterthought rather than a stealthy fighter with good maneuverability. Point is, you're right. The buyer's priorities in the ATF competition was practicality first, and honestly militaries should all be putting practicality first. i.e. the T-14 sucks even though everybody's crying about how "amazing" it is.

@JohnK in the case of non-reversible hydraulic control systems I don't think an all-moving rudder is free-floating; therefore it does provide the same stabilizing yaw effect ("weathervane" effect) as does a fixed fin of the same size.  We see the same in radio-controlled planes-- some rc gliders have all-moving vertical fins and many have all-moving horizontal stabilizers and since the surfaces are connected to servos and not free-floating, the dynamics are quite different than we'd see with an all-moving surface connected by cables and pulleys to a control stick or pedals.  Food for thought--

@quietflyer: At the maximum dynamic pressure of an F-22/23 the yaw stability is determined a lot by aeroelasticity, which gives a fixed vertical an edge. With active stabilisation, however, both flight dynamics and aeroelasticity can be compensated, and the remaining advantages of the all-moving vertical are indeed only at supersonic speed and in stealth. Given the higher complexity and possibilities for failure of active stabilisation, the fixed vertical is the more robust solution.

A primary reason the F22 won out over the F23 was Northrop's huge cost overruns on the B2.


text:
What is the true top speed of the SR-71?
By "true" top speed I mean the absolute fastest horizontal airspeed the aircraft can achieve if damage to the engines is disregarded (similar to how the MiG-25 apparently can reach mach 3.2 but may damage its engines beyond repair). Catastrophic structural failure (of anything beyond the engines) is not permissible in this scenario.
In "The Untouchables" Brian Shul claims that he reached mach 3.5 while evading a missile. This is also stated in the Wikipedia article on the SR-71 with a citation to the same book.
Are there any other sources than his own book that can confirm or reject this claim? Can it be argued for or against this top speed claim on technical merit or physical limitations?
On Wikipedia it is also stated "Maximum flight speed was limited by the temperature of the air entering the engine compressor, which was not certified for temperatures above 800 °F (430 °C).[57]"
However, it is not clear how much abuse beyond this the compressor could take. It is possible to give some estimate or educated guess based on the materials used?

I also suspect that, but the question is written such that it is possible to answer it with arguments regarding what would physically be possible based on what is known about the SR-71. Perhaps you can argue based on the construction of the materials? The limitations in the variable geometry of the intake? Something else? If there was some simple source available that officially states "this is the actual top speed", obviously Wikipedia and others would have since long started to cite it.

This is actually a good question, but it's beyond my knowledge of the plane to calculate. So, not an answer, but an estimate based on similar overspeeds for other aircraft would place the zero safety margin point for horizontal speed somewhere between Mach 3.4 and 3.55. Something a bit above that could be possible if you count momentary airspeed in a dive (before the air gets dense and slows it down again).

I suspect the „fastest speed the aircraft can achieve“ in your scenario will be achieved diving towards the ground at full thrust. This is certainly faster than anyone ever cared to test, and I strongly suspect that any available engine performance tables for the aircraft would not cover a speed range fast enough to accurately model this... also, I don’t know whether structural failure is permissible in your scenario, but I‘m sure that it quickly becomes a limiting factor in a full thrust dive.

@CptReynolds Very good point. I edited the post to make it horizontal airspeed. Destruction of engines is permissible, not catastrophic structural failure.

I once worked with a guy who had been an aircraft instrument tech in the USAF. He said he had serviced some instruments in an SR-71 once. All the gauges were covered with metal disks, so he couldn't see the top range of anything he wasn't working on. I asked if he had been tempted to peek. "Nope. There was an armed marine standing over me with orders to shoot if I did."

Based on the SR-71A operational envelope, the top Mach number was Mach 3.3 when authorized by the commander and Mach 3.2 otherwise. The top airspeed was 400 kts equivalent airspeed when supersonic and 450 kts equivalent airspeed when subsonic.

The graph says Vmo (Vh) 450 KEAS, not 400 KEAS.

@JanHudec Thanks! Posted too quickly. Corrected with subsonic/supersonic values.

Mind that this is max allowed operational speed, not the max speed the aircraft is capable of surviving. There will be some safety margin there, making a max emergency speed of 3.5 believable.

@jwenting So it's to PIC discretion if he wanted to take his chances with the missile or out running it

@jean of course. In emergencies, stated limits and procedures go out the window and pilot judgment takes over. Better to burn out an engine or cause some excess structural stress on the airframe than have the aircraft and crew blown out of the sky over hostile territory.

The SR-71 Pilot's Operating Handbook has been declassified and is available online.  The operating limitations section states that Mach 3.17 is the recommended maximum cruise speed for normal operations.  Speeds of up to Mach 3.3 could be authorised by the commander as long as the maximum CIT (compressor inlet temperature) of 427 degrees C was not exceeded.  So while it might be possible to exceed the maximum Mach, doing so probably carried with it the risk of Bad Things(TM) happening.

Welcome to Aviation SE!

Of course, in the referenced example it was a question of choosing between two Bad Things.

The USAF never did release just how fast an SR-71 CAN fly, preferring to state that it DID fly at certain speeds on certain dates and set certain records.
Maj. Brian Shul made references in his books to the jet attaining Mach 3.5+ during flights he flew over Libya evading SAMs.  I believe him.  There are also credible rumors that a Blackbird was capable of Mach 4 in ideal atmospheric conditions.  If USAF or CIA Sled Drivers did attain that high of a speed on certain occasions, they’re not confirming it.
Most Blackbird pilots were pretty coy about a top speed.  Shul liked to say that the muzzle velocity of a high powered rifle bullet was about 3000 ft/s.  A Sled comfortably cruised at 3,300 ft/s and the Pilot still had a couple of inches of throttle left in case he REALLY needed to haul ass!


text:
Why doesn't the air force order more F-22's?
I've come across several articles touting the F-22 as the most formidable air-to-air killing machine to date, such as this one:
https://nationalinterest.org/blog/buzz/f-22-nearly-unstoppable-air-force-has-too-few-them-32152
However, this article and others are also quick to point out there are too few of them.
It is not clear to me what the problem with restarting F-22 production is. The cited article appears to state that the USAF will focus on the sixth generation of aircraft, and integrate the F-22 into that.
Doesn't this seem like a huge gamble? When will sixth generation aircraft be ready in massive numbers?
There are new F-15's and F-16's being built, even today, and they still comprise the bulk of the entire USAF inventory. I don't buy the argument that they can simply "skip" the fifth generation in terms of air superiority fighters and wait for the sixth generation.
With the F-35 being in full production, is it really that hard to restart F-22 production as well? I'm aware that probably nothing at all on the F-35 can be just bolted on to an F-22 airframe -- but shouldn't advances in avionics on the F-35 (if any) only compliment a restarted F-22 production?
It seems at least plausible that the personnel and facilities involved in making F-35 would be able to be adapted to build new F-22's.
However, I'm sure it isn't as plausible as I imagine, and I'm just curious what are the reasons.

"It seems at least plausible that the personnel and facilities involved in making F-35 would be able to be adapted to build new F-22's." Why? They're busy building '35s. Your argument seems to be similar to the child who says, "Daddy, you can afford a new car for yourself, so why do you say you can't afford [expensive toy] for me?" And the answer is that it's precisely because he bought the new car that he can't afford to buy any other expensive things.

So your answer is that they simply can't afford it, even though there is a strong need for it? The F-35 is not an air superiority fighter so I'm not sure I see the logic there.

For one thing, the Air Force does not build airplanes.  They order them from civilian companies - Lockheed-Martin, in the case of the F-22.  So the Air Force would have to decide they want more, request a bid from the company, then go to Congress to get the money appropriated.

@jamesqf Fair point. I've updated the title of the question.

Aside from Juan's point about the F-22 being fairly outdated by now (it's an 80's era design), it is also not possible to just restart production of it.
First, it would cost ~$10Bn to simply get to a place where you can produce the an F-22 again. That doesn't include the actual cost of a single plane, just the money required to re-equip factories, train workers, produce a new engine since the old one is end-of-life, etc. Source
This estimate is assuming that the project was left off in the state Lockheed claimed it was. There is reason to believe that some of the tooling for the F-22 no longer exists at all. Source
Finally, the F-35 program has, in my opinion, shown that there is not so much to be saved by re-using components if the overall process is not efficient.

I'm accepting this answer as it is cited with two sources.

Cost and relevance. The aircraft are very expensive to produce and the Air Force doesn't get enough budget to build more. In addition, the need changed. The F-22 is not as relevant in places like Iraq and Afghanistan, where air superiority was not as much an issue as the need for other types of aircraft such as bombers and ground support birds. With the changes in the landscape from new Russian and Chinese aircraft, there was discussion about restarting the F-22 production line, ordering new aircraft and upgrading the existing fleet, but the price was considered highly prohibitive. There are upgrades to the fleet scheduled to begin in 2024 (mid-life upgrade program) though, so the aircraft will be in service for a while.

The article addresses this too, I believe. The threat during the cold war disappeared, the need for the F-22 disappeared. However, now there is a need for it again, with threats from other fifth generation fighters from other nations.


text:
What happens if full collective pitch is suddenly commanded on most modern helicopters?
Related, but not the same: What happens when you apply full cyclic + collective?
If the pilot suddenly applies full collective pitch on a turbine powered helicopter, will the engine stall? It seems from the other question, that this is not typically mechanically limited, so it is possible to force this onto the helicopter. However, does it cause the engine to stall? Any other problems?

I'm guessing that the rotor RPM would drop and if left to deteriorate the blades would stall. Are you asking about piston helicopters or turbine?

I'll assume you're talking about typical turbine helicopters.  The fuel controller on a helicopter's turboshaft is used to regulate rotor RPM via its gas generator's (the compressor/burner/turbine section) speed and torque.  The RPM governor setting is coarsely set with throttle, then fine tuned with a trimming function controlled by a toggle (blip) switch on the collective to set the precise rotor RPM the governor will maintain.
The fuel controller will now govern rotor RPM automatically at that setting as you load the rotor with collective, by increasing fuel flow to increase the torque output of the gas generator.  So torque, fuel flow and Turbine Outlet Temperature (TOT) will all rise as you pull collective.  Both torque and TOT have operating maximum limits, so how much collective you can pull is therefore limited by a torque and/or TOT red line.
Trying to take off in marginal conditions due to load, temperature or altitude, you will find yourself pulling pitch until you are at a TOT or torque limit before you can even hover, and if you really really had to get airborne (like say you were an overloaded medivac Huey in Vietnam), you'd have to get the machine sliding along the ground first to get some translational lift in order to take off (one big advantage of wheeled landing gear).
Anyway, it's a hydromechanical fuel controller/speed governor that just does what it is told, so if you just haul the collective all the way up just sitting there, it'll depend on how much fuel the controller has to dump in to maintain RPM as you shoot off the ground straight into the sky.  You will probably exceed the TOT or torque limit or both, making it a very expensive takeoff.

Exceeding these limits severely, wouldn't that cause the turbine to flameout?

That shouldn't happen.  The fuel controller regulates fuel flow to keep the correct air/fuel ratio in the burner can so it shoudn't cause an overrich mixture or anything like that.  In very early jet engines the thrust lever was not much more than a needle valve so if you applied too much it would dump fuel in and flame out or let the flame grow too big and burn up the turbine.  Hydromech fuel controllers respond to your power command but manage the fuel flow relative to mass air flow while they do it.  But if you command too much power they won't stop you.  FADEC engines will however.

No I get that, in a plane, if you suddenly give full thrust, without a closed loop system to control fuel you could flameout. But in a plane, there isn't anything that will literally act as a sudden, huge mechanical load on the engine. If you give full collective pitch, doesn't that literally slow down the turbine drastically? If you slow it down below a certain RPM, surely it will just flameout? Or do I fail to understand the mechanics even on a very superficial level here?

Well there is going to be some lag between detection of RPM decay and responding by dumping fuel into the engine, so if you yank the collective up as hard as you can, you will probably get both; some decay in RPM plus temp going through the roof as the governor tries to stop the decay.  On a free turbine turboshaft like a PT-6 the power turbine is just sitting in the gas generator's exhaust and the governor just makes the gas generator blow harder on it when you call for more torque by pulling collective.


text:
Why does the autopilot disengage even when it does not receive pilot input?
After having read the disturbing
https://en.wikipedia.org/wiki/1999_South_Dakota_Learjet_crash
I'm left with the question as to why the computer allows for the autopilot to be disengaged when there is no pilot input.
Why doesn't it engage the stick shaker and alarm as normal, but maintain control until pilot input is received, or require the pilot to manually disengage the autopilot?
I'm not a pilot, so I'm sure there is good reasoning behind this. However, from my own naive perspective this is why it seems foolish to automatically disengage the autopilot:
This is what happened after the autopilot was disengaged:
"The target is descending and he is doing multiple aileron rolls, looks like he's out of control...in a severe descent, request an emergency descent to follow target."
Imagine that the crew did regain consciousness, they would find themselves in a disorienting situation, with an aircraft possibly damaged from aerodynamic stress when approaching mach 1 in an uncontrolled nose dive. This, compared to the autopilot simply maintaining attitude as best it can.
Until finally, this: "the aircraft hitting the ground at a nearly supersonic speed and an extreme angle."
The alternative being, with no pilot input that the aircraft would have maintained a somewhat stable attitude, deploys its landing gear, flaps, and prayed for the best -- that there just happens to be a fairly smooth piece of land, with no major obstacles in the way?
Now, I'm aware that all six on board were dead before the plane crashed. That doesn't mean there are no situations where a controlled crash landing is not preferable to an uncontrolled crash.
I'm not an avionics software engineer, so forgive me if I don't appreciate the complexity of the task -- but as a software engineer and someone with an IT education it seems to me almost trivial to extend the functionality for the aircraft to accommodate for this scenario with a mostly hard-coded procedure---yes, blindly landing at whatever is there and hoping (and with the system being extended with visual processing, perhaps, in the future). While I'm not even going to sketch a full proposal for such an extension here, it is part of my motivation for asking this question in the first place, so I'm simply mentioning it as that.
I can also mention, although I'm sure anyone qualified to answer this question will know about this case (and know it far better than I do), the Cornfield Bomber https://en.wikipedia.org/wiki/Cornfield_Bomber so if this is possible without any help from the computer, surely it would be possible with help, even from a computer that only has basic instruments (altitude, attitude, etc.) and no vision, yet simply attempts it "blindly" as far as visual processing is concerned.
Please keep in mind that I'm under no illusion that the plane will land without a scratch. This is a game of statistics, such as all safety procedures, and it seems (naively, I'm sure) that this might increase the chances of survival by some (probably slim) margin.
My own attempt at an answer:
I can only imagine that the reason such functionality doesn't exist, is because it is so rarely useful and considered too much of a curiosity. However, other crashes that also appear to be highly unlikely in general, have seen changes enforced in the aviation industry. So this isn't really a good answer.
The only other thing I can think of, is the omnipresent fear of AI. The idea to implement some AI, that could potentially, when given full authority of the plane, glide it into a building unintentionally, is just unthinkable for obvious reasons. While I sympathize with this view, I don't see why this is more likely than it happening with a plane flying without such a simple AI---both the AI and the completely uncontrolled plane would be flying just as blindly, both at risk of hurting innocent bystanders. The only difference is that the AI assisted plane flying autonomously (despite mostly blindfolded) does have a marginally higher chance of allowing for some survivors.

Note that part of what happened on N47BA is that the crew apparently didn't put on supplemental oxygen immediately, but were likely trying to figure out a difficult-to-comprehend checklist item in an already-stressful situation. Had the first item on the checklist been "oxygen masks - don", or either pilot had just thought "we're losing pressure, don't futz with the checklist yet, just don that oxygen mask now!", it's likely that the outcome would have been very different, and my understanding is that in response to that accident, such a checklist change was made more or less across the board.

Essentially autopilots are much, much simpler than one would think.  They're not even vaguely like "a self-driving car".

@Fattie Yes, but this is the question: Why are they this simple? Keep in mind that I'm suggesting why it doesn't continue to maintain control (and land blindly, which is better than crashing). It already is able to maintain control, isn't it? I'm not suggesting a major software overhaul (although I'd very much like to see one). I'm merely suggesting why the already simple functionality isn't only marginally extended.

hi Alph - hmm, purely FWIW I would not see that as simple. You know the (mechanical) auto-tiller on sailboats which solo sailors use.  Strikes me it's more like that.  Closer to a mechanical thermostat than a "self-driving car" as we now pretty much think of them.

The "autopilot" is a fairly basic control system. Usually it is composed of just a few components (logically speaking) like a wing-leveler, heading mode, and altitude mode. The autopilot can control the aircraft usually through servo's connected to the control cables or through the hydraulics. External systems can feed into this to do things like follow a descent path, follow GPS/VOR routes, etc. The autopilot itself is basic.
The autopilot is designed to fly an aircraft that does not otherwise have any other issues. The autopilot is not designed to fly outside of normal operating circumstances. This means that when some kind of abnormality is detected (usually through the autopilot hitting its programmed limits) it will automatically disconnect.
In the Learjet case you cited, the autopilot continued to maintain altitude after the engines failed, but because maintaining altitude without engines means your speed will decrease, the autopilot disconnected before the aircraft stalled rather than fighting the pilot through a stall. It assumes that it is safer to automatically hand-off than require the pilot who is now trying to stabilize the aircraft to also have to worry about disconnecting the autopilot.
Most autopilots give some kind of warning that they've disconnected. This can be things like a chime, voice alert, stick shaker, etc. It's the autopilots way of saying "I've reached the limits of what I can control, you need to take over now". Otherwise it could potentially make a situation much worse.
The cornfield bomber was not on autopilot when it crashed. It just regained stability as a result of the ejection and remained on a fairly level (but descending) path until it bellied into a field (and continued to run/move for quite some time).

You beat me to it. +1 for the "Otherwise it could potentially make a situation much worse."

How can it make a situation much worse when there is no pilot input? Isn't an aircraft that has some control by the autopilot more safe than one that has no control at all? If it is a matter of fear of the autopilot making sudden, unwanted movements in the case of sensor failures, etc then wouldn't this trivially be solved by having a time delay from a programmed desire to disengage, before (in the event of no input at all) the autopilot re-engages and attempts to maintain some sort of control? I understand that some autopilots have little to no software involved, but surely capabilities vary?

@AlphaCentauri Let's say you have heading and altitude mode engaged and you lose your left engine. The right one is only at 50% throttle so it can't maintain altitude. As your airspeed bleeds off, you will start to yaw to the left. Now you are uncoordinated approaching a stall... what happens next? As you enter the spin, now you have the autopilot applying rudder for you, which you don't want. Hurry up, disengage the autopilot, feather the left prop, ailerons neutral, elevator down, rudder against the turn. Do you remember where the button is to disengage (it isn't always on the control wheel)

With my idea, and in my scenario (no pilot input)? The autopilot disengages immediately, waits some reasonable time (say 10 seconds) for pilot input, then re-engages if there is no pilot input. After re-engaging, is will attempt to use whatever authority it has over the plane to keep it level, even if this involves bringing the nose down. Without my system, the autopilot would disengage and never come back. With no pilot input, the plane would probably do rolls like in the 1999 Learjet case and eventually (almost certainly) crash a lot harder than during a somewhat controlled crash.

Aircraft are naturally stable, they should return to a level flight (within an envelope) if they are left with no inputs (hands off). This is why just "letting go" is sometimes better than trying to fight it. For example I believe the C-152 will happily exit a spin if you just "hands-off". The learjet you are talking about wasn't doing rolls in level flight, it was pointed almost straight down at the time...

@RonBeyer ['s first comment]: So have the autopilot automatically open the throttle on the remaining engine.  Aircraft already have autothrottles; it shouldn't be too hard to add engine-failure-compensation logic to that.

Other answers already stated that autopilots are essentially very simple things. Especially for someone with an IT background.
In some autopilots, there are modes for such events. For example, some G1000/G3000 on light jets are equipped with Emergency Descent Mode (EDM). What does it do?

Automatically activates when cabin pressure is lost above a certain altitude (~30000 ft).
Sets Altitude Hold for 15000 ft. This is a compromise altitude where air is breathable but no obstacles are expected.
Changes course to 90° to the left so as not to descent through an airway.

Simple, and very far from AI. Furthermore, it gets worse by the fact that on many aircraft, and most light aircraft, there is no autothrottle, or if there is, it is often decoupled from the autopilot. So, if the pilot is unconscious and cannot reduce thrust (and ideally deploy speedbrakes), this 'emergency descent' turns into a smooth cruise descent at the maximum allowed airspeed, some 300-1000 fpm, if any at all.
Once again, this is rather a tool to reduce workload, rather than a 'pilot'.
Why so? This is a separate philosophical question. But generally, while a human pilot is ultimately responsible in the cockpit, the pilots (and aviation in general) prefer known deterministic solutions rather than unpredictable 'intelligence'. Many incidents already stem from pilots' confusion about what the aircraft is doing; adding 'smarts' here can add to that. But may improve in some cases. There is just no obvious answer like 'just throw more computing power at it'. Just think of the 737MAX/MCAS ordeal.

Note that Emergency Descent Mode was developed in direct response to the South Dakota Learjet crash cited and has far lower complexity (and thus risk) than the OP's proposed solution.

The autopilot is designed to do exactly what it's told, until it can no longer safely do so. At that point the situation is beyond what the autopilot is designed for, so it hands control back to the pilots. Even modern autopilots aren't designed to do much descision-making on their own, let alone a Learjet designed in the 1970's.
Adding some sort of functionality to "fly the plane down" in such a situation would add complexity to the system for very little benefit. This sort of situation is fairly rare. And most of the world is water, with much of the rest being not very flat. It's extremely unlikely that for all that effort such a system would be able to make any survivable landings.
And even if it could make a survivable landing, we're talking about crew and passengers that could have been passed out for hours, and might not surive that anyway. Perhaps there's some value in a sort of "dead-man's switch" that would automatically bring the plane down if the pilots fail to respond, but this has most of the same issues above.
There's also the issue of adding yet more automated features to the flight controls. How do we handle situations where this malfunctions, and starts unexpectedly descending the plane for no apparent reason? That sort of thing would be especially unpopular right now.
Some fighter jets do have a system called Auto-GCAS that is designed to stop an unconscious pilot from flying into the ground, but that's a much more simple problem to solve than getting on the ground safely.

In case anyone is interested, here's a video of an Auto-GCAS.

The cruise autopilot behaves this way by design. From this answer: design parameters for aircraft system safety.

For airborne systems, a very thorough analysis is made on failure probability and on failure modes.

A safe failure mode is: the system stops functioning completely. An unsafe failure mode: an unintended output, such as a hard-over fail of a hydraulic actuator with a stuck servo valve.
Also, you want the system to only carry out its intended function. It is hard though to predict everything that can ever happen, and both for safety and cost reasons the system is simply completely disengaged and the pilots notified.

The cruise autopilot has relatively low reliability requirements because the pilots take over when the system fails. At cruise, there is sufficient buffer in altitude and reaction time for a response to autopilot failure, so the A/P is designed to be Fail Passive: it simply disconnects upon any detected anomaly, while notifying the pilots. "Your job now."
Notice that the autopilot functioning during landing, the CAT III auto land capability, has much more stringent safety requirements: functional failure less than once every million hours instead of once every 1000 hours for the cruise autopilot. This is because during landing the ground is very nearby, speed is very low, and there is no time for safely transferring control to the flight crew. So the auto land system is designed to be Fail Active: three redundant channels perform exactly the same job, upon failure of one of these the other two disengage the failed channel and continue automatic landing.
With the cruise autopilot, no redundant channels are required because there is a flight crew :)

I love the diagram type. I've never seen it before, but it's a nice way to conceptualize reliability.

The general philosophy is that autopilot is a tool, not an extra pilot, and as such, it disengages when anything goes seriously wrong.  Inertial sensor failure? Engine loss? Unusual attitude? Hand control back to the pilots with a nice warning sound. This option isn't taken lightly, especially in high-workload situations like landing, but it's the general solution to rare conditions.
Yes, it may seem from a software perspective like a small feature to add robustness here and there's certainly room for innovation, but the cost and liability to develop for rare and even dangerous situations is generally not worth the rare benefit it provides. For example, here the autopilot disengaged because the plane went below stall speed or vmin.  The standard solution to a stall is to descend and increase throttles to build up speed again, but automated stall recovery has complications like traffic and terrain avoidance, and thrust-management integration.  Automated stall recovery is especially tricky when you have no fuel as in this incident, or back in 1999 when enhanced TAWS and TCAS II was fairly new and before GCAS.
Additionally, preventative solutions now exist that make the cost-benefit analysis here even more lopsided.  First, it should be noted that in general, planes are stable and flying without pilot or autopilot input causes the plane to fly more or less straight and level, although that did little good here. Automated pitch-based low-speed protection or AoA protection are standard on some aircraft like Dassault jets. Airbus and other companies have developed a rapid/emergency descent feature to handle incapacitated pilots due to depressurization. Fighter jets are developing an auto-GCAS as fooot has mentioned that's already saved the lives of some incapacitated pilots.

I think the general design philosophy is that if the auto pilot were to merely politely indicate that a human pilot should take control, that may lead to situations where a human thinks the autopilot is flying the plane when in reality nothing is controlling it.  That having been said, it might be useful to have a "human emergency" switch to indicate to the control system that even though there should always be a human in position to take over at a moment's notice, reality has intervened.  Rules may forbid the use of such a switch in non-emergency situations, but if, e.g., ...

...an aircraft has two pilots on board and no other personnel, and one of the pilots goes into unexpected cardiac arrest during what's expected to be straight and level flight on an IFR-cleared path, I would think having one pilot try to rescue the other after triggering an automated "human emergency" distress call and setting instruments to fly the plane, would be better than simply letting the incapacitated pilot die.

@supercat The current generation of autopilot will already accommodate that scenario in normal flight  , however if there is both an airplane and pilot emergency , from a triage perspective the non-incapacitated pilot should probably continue to fly the plane.

@crasic: A pilot who is expecting or handling an airplane emergency should obviously remain at the controls, but if dealing with a "[possibly human] contents of airplane" emergency during seemingly-normal flight has caused the pilot to leave the controls, the risk calculus of whether unexpected turbulence should cause an autopilot to hand controls to the pilot who isn't there, or attempt to fly the plane as well as it can until the pilot gets back, would seem to favor the latter even though, with a pilot present, it would favor the former.


text:
Why is Thunderbird 5's number upside down?
Why is Thunderbird 5's number written upside down?

So it's right side up when doing inverted manoeuvres?

@GregHewgill turns out you are correct :)

Good question and nice catch.

@CGCampbell thanks :) What would also be cool to know is if number 5's engine number has always been upside down, or only since the Thunderbirds got the F-16's

@CGCampbell Updated my answer, though I am not sure why the older Thunderbird 5's had the number right side up. should I make a new question about that?

@flyingfisch -- re "though I am not sure why the older Thunderbird 5's had the number right side up. should I make a new question about that? " -- I think it's because the plane would look kind of silly with a great big tail number painted upside down.  It probably wasn't till they went to a smaller number painted in a less conspicuous place that somebody thought "hey, wouldn't it be kind of hipster (but still in a military-conforming kind of way) to paint the number upside down?"

This is because Thunderbird 5 is the opposing solo, and spends almost all of its time inverted.

Apparently though, this plane's number was not always painted upside down:

Just guesswork on my part, but maybe the Thunderbirds did not fly inverted maneuvers before the F-16s?

According to http://www.burrusspta.org/video_files/thunderbirds.html they did use inverted formations at least as far back as 1964 in the F-105's.

also, I have no problem at all if you want to unselect my answer and select your own. You've got the more research effort showing.

@CGCampbell oh ok, then I guess I will. ;-)

@CGCampbell they did, but older types were less suitable for SUSTAINED inverted flight, so they'd spend the majority of their display sequence "right side up".

The #5 is painted upside down because it represents how the lead solo spends most of his time during an aerial demonstration. Dennis Graham USAF "Thunderbirds" Alumni 1985-1989.

Welcome to Av.SE -- It's always good to have folks on here who've been part of teams like the Thunderbirds.  This answer is fine, although it doesn't really add anything to the existing answers; if your future answers can offer more than what's already present, that would be great.  Again, welcome to Av.SE, and please do come back often!

Just for clarification sake, Thunderbird 5 is the LEAD solo, not the Opposing Solo.  Opposing Solo is Thunderbird 6.  The 5 is upside-down because During the show he spends the most time upside-down.  On crowd passes, and show center, he is usually inverted.
Also, the F-4 Phantom and T-38 Talon fly perfectly well inverted.

Thanks for clarifying the facts! Based on their site and this video I'd say you are correct.

When the Thunderbird's fly the reflection pattern, one plane will be right side up flying level. Number 5 will be upside down and below the first one. They are like reflections in a mirror, bottom to bottom. Number 5's engine number is written upside down, so that it can be read correctly. If they fly the calypso pattern, where one plane is flying right side up and the second will be above it, upside down, the upside down plane will always be number 5.

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/3.0/


text:
Why are most cockpits gray?
Russian cockpits were often painted turquoise to reduce pilot fatigue. So my question is why most non-Russian cockpits are painted gray, or in the 777's case, tan?

I paint my cockpits mauve.

So you can tell ag a glance that you are not on a Russian airliner/

They say taupe is very soothing.

Basically, neutral mid-toned greys or tans are considered to be the best color to use, because they aren't any other color:

The base color shouldn't be confused for anything in an instrument display. This precludes using red, yellow, green, bright blues or brown, but also black and white as black is used to represent empty space in instrument displays while white is commonly text and also used for other display elements.
The color shouldn't cause glare. Too light a hue will increase sunlight scattering in the cockpit, reducing pilot visibility in high-sunlight situations.
The color shouldn't be too dark, as in those same situations a dark color will absorb the sunlight and become hot, increasing ambient temperature of the flight deck, requiring additional cooling system capacity for both pilots and instruments (many civvie aircraft have black instrument panels, but other elements of the design typically prevent the panel catching too much sunlight).
The color has to be relatively easy to find or make, allowing touch-ups. Brighter colors are harder to match exactly; neutral tones blend easier and aren't as distracting even if they are slightly mismatched. This is mainly a military concern, where crew chiefs do what they can with what's on hand; commercial airliners will have hundreds of gallons of their livery colors and other standard touch-ups including cockpit-approved colors available at maintenance hubs.
Western thought says the color should be visually uninteresting in order to provide the minimum distraction to the pilot from more important colors in the cockpit. This is where Western and Russian thought primarily differs; Russian designers favored a "mood color" over being completely nondescript, while Western designers favor the background color "disappearing" even if the net effect is depressing to a pilot sitting in it for several hours a day.

To be fair, Western cockpits are not always grey or tan, but really there are only a couple more common options. European Mirage, Rafale and Gripen fighters are commonly seen with a sky-ish blue interior, providing some of that mood color benefit while remaining nondescript. Aircraft cockpits in WWII, on all sides, were painted in whatever the crew chief had available, which usually amounted to land-based planes getting the same olive drab that coated every piece of metal the Army owned, while naval variants got one of the various blue-grays used on the ship itself.

all_licenses: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/3.0/


text:
Why did moving the CG aft on the Wright Brother's plane improve handling?
In response to Peter Kämpf's answer to this question, why did moving the CG back on the Wright Flyer improve its stability?

It did not improve stability, but flyability.
The Wright Flyer had the CG located aft of the neutral point and was unstable in pitch. A longitudinally unstable aircraft will deviate from its trim point, and when flown by a human pilot, will have a wavy flight path. The Wrights called this undulation. It is caused by the delay in the pilot's response and his tendency to overcompensate, so the aircraft is oscillating around the trim point (= the angle of attack where all moments around the pitch axis are in balance). This delay is more problematic when the eigenfrequency of the motion is higher. All Zeppelins were unstable in pitch above a certain airspeed and in yaw over the full speed range, but nobody bothered. These things were so big that any motion needed a long time to develop and deviations from the trim condition were easy to correct.
With aircraft, things are different, because they are more maneuverable and much smaller. The characteristic parameter here is the short period mode which characterizes the pitch motion. Its frequency is around 1 Hz for small aircraft and can be approximated like this:
$$\omega_{\alpha} = \frac{v_{\mathrm{trim}}}{i_y} \cdot \sqrt{\left(\frac{c_{m\alpha}}{\mu} + \frac{c_{L\alpha}\cdot c_{mq}}{\mu^2}\right)}$$
Nomenclature:
    $\omega_{\alpha} \:\:\:$ Eigenfrequency of the short period mode
    $v_{\mathrm{trim}}\:$  trimmed airspeed
    $i_y \:\:\:\:\:$  Radius of inertia around the pitch axis
    $c_{m\alpha} \:\:$ pitch moment gradient over angle of attack
    $\mu \:\:\:\:\:\:$  reduced mass. $\mu = \frac{2\cdot m}{\rho \cdot S \cdot l_{\mu}}$
    $c_{L\alpha} \:\:$ lift coefficient gradient over angle of attack
    $c_{mq} \:\:$ pitch damping coefficient
    $m \:\:\:\:\:$  mass
    $\rho \:\:\:\:\:\:$  density of air
    $S \:\:\:\:\:\:$  reference area (normally wing area)
    $l_{\mu} \:\:\:\:\:$  mean aerodynamic chord
To answer the question, all it needs is the first factor of the equation. The frequency increases with airspeed and goes down with the pitch inertia of the plane. By adding a weight at the back of their airplane, the Wrights increased this pitch inertia, thus lowering the eigenfrequency and making it easier to control. Make no mistake: The Flyer became even more unstable, but the instability became easier to correct because the deviations from the trim point built up more slowly.
Modern replicas of the Flyer have their CG ahead of the neutral point and are naturally stable.

+1 excellent explanation. I did not realize that sometimes making a plane slightly more unstable improves its handling (as you mentioned, due to increased inertia). I've noticed this myself on one of my RC planes with CG so far aft that neutral trim required down elevator. I couldn't explain why it flew for a very long time.

What about mentioning PIO?

@yankeekilo: That is what the Wrights called undulation. I used their terminology because I find it very descriptive. But, yes, this was an early case of PIOs, and they got less intense when the aircraft's eigefrequency was shifted away from the eigenfrequency of the control system (this being Wilbur or Orville plus the Flyer's pitch control).

For a plane to be stable, small control input should lead to small corrections. Also, small air currents should lead to small deviations.
Now consider what happens when the Flyer pitches a bit down. It picks up speed, and the wing generates more lift. If the CG is to far forwards, the wing lift generates torque which pitches the nose even further down. In other words, that small change is amplified.
Moving the CG aft reduces the torque change on pitch changes, which means that small changes remain small - and thus the plane is stable.

Moving CG forward makes the aircraft stable. For both planes with regular tail or canard (Flyer was a canard). The reason is that with forward CG the forward surface flies with higher angle of attack. The Flyer had the CG too far aft and was not stable. (-1, this is incorrect explanation).

@JanHudec: I can't find a good source which states that the Flyer had its canard at a higher AoA. With a canard generating upward lift, you must have a CG between the canard and the wing (obviously, else the two torques cannot cancel at all). Moving it a bit forward or afterwards between those limits alters the balance of torques, but you cannot generalize and say that the CG forwards is stable. Just put the CG at the location of the canard and stability becomes impossible.

Relative AOA of the control surface and the main wing is a function of the centre of gravity, not the other way around. Because the pilot adjusts the canard to balance the craft. Flyer had the canard at lower AoA than main wing, because it was not stable. But moving it's CG forward would make pilot increase AoA of the canard and therefore improve stability. But Wrights never moved it forward far enough to make it stable. And as Peter Kämpf correctly explains, moving it forward a bit made it less controllable and moving it aft a bit made it more controllable. Though less stable.

Aircraft with CG at the location of the "canard" could easily be stable. But it's "canard" would be the main wing producing all lift and the "wing" would be a stabilizer flying at 0 AoA in steady flight. Such configuration would be stable just fine.

@JanHudec: That's a bit of a naming issue then: I use canard to mean a control surface forward of the wing, which can generate torque in order to alter the pitch as needed. To generate torque, you need a lever, and the lever is by definition 0 if the CG is located at the canard. You can of course have the wing at the CG if the control surface (canard or tail) generates 0 torque under normal conditions.

I use canard to mean exactly the same. To generate a torque, you indeed need a lever. But for stability it does not matter which of the two surfaces generates the torque! An aircraft with centre of gravity coincident with centre of lift of the forward lifting surface (and controls on that surface; they don't matter at all; controls don't move when we analyse stability) is stable. If it pitches down, the angle of attack of both surfaces reduces. The forward surface does not start generating any torque. But the rear now flies at negative AoA and causes restoring up torque.

The condition for stable aircraft is simple. The forward surface has to fly at higher angle of attack than the aft. Independent on which is control surface. Moving centre of gravity forward means you have to increase lift, and therefore angle of attack, on the forward surface relative to the aft surface, which increases stability. Moving centre of gravity aft means you have to decrease angle of attack on the forward surface and therefore reduce stability. Flyer was not stable. The reason was it had it's centre of gravity too far aft. You say forward in your answer and that's not correct.


text:
Has a commercial passenger airliner ever had its cockpit fully upgraded?
In an earlier question What are the barriers to feasibility of stratospheric cruising for commercial air travel? (i.e. Concorde?) it was suggested that Concorde was not properly maintained as its analogue flight deck had never been upgraded.
Concorde production ceased in 1979. Fourteen Concordes saw commercial service. By end of operation in 2003 there were nine Concordes in use.
Excluding the military, has any airline or manufacturer ever retrofitted a new design of flight deck to an existing fleet of old commercial airliners?

I doubt the cost would be warranted to do that, unless some safety regulation came out of the FAA but most of the time you can retrofit only the new requirement without needing a full upgrade

While many times an upgrade is not economical for older airplanes, sometimes the new features make it worth the cost.
Two examples I found were Southwest upgrading their 737-300 fleet, and Delta upgrading their MD-88 and MD-90 fleet. The second article also mentions American and Icelandair 757 and 767 upgrades. The Southwest and Delta upgrades involve over 100 aircraft in each case, which probably helped to make the upgrades more economical.
In both cases, a major factor mentioned was the ability to perform required navigation performance (RNP) procedures with GPS and other modern features. As the FAA works to implement the NextGen ATC system in the US, these upgrades will offer more benefits for the operators.
Also, I'd like to comment on the following statement:

Concorde was not properly maintained as its analogue flight deck had never been upgraded.

Proper maintenance and technology upgrades are not always the same thing. Aircraft with older systems can be maintained just as well as newer planes. We have airplanes that are 50 years old or older, like the DC-3, which are still flying. While technology upgrades certainly have benefits, aircraft with analog cockpits are still operating just fine around the world. They may not be the most modern machines out there, but proper maintenance is what has kept them flying this long.

AFAIK the main reason for both programs you mention was to create fleet commonality between older and newer variants of the same aircraft (773-300 with NG for example).

It's also not THAT expensive. $200-300k per aircraft in those two examples, which isn't small change but is still only around 0.25-0.6% of the cost of a new aircraft (Based on around $50m for an MD-90, $100m for a 737)

"Proper maintenance and technology upgrades are not always the same thing" -- I think the original statement means "properly maintaining your product", as a competitive and attractive offering. As you say, very different from "properly maintaining your aircraft", that is to say stopping bits falling off. Whether a high-tech cockpit would have maintained Concorde as a product is still debatable, I suspect. It was never re-ordered, I doubt that a fancy cockpit would have changed that in the face of the other relevant factors...

There's also the MD-10 upgrade to the DC-10.

The MD-10 program allows operators to retrofit DC-10s with a new,
  advanced- technology flight deck. Benefits of the retrofit include a
  two-person flight deck, weight savings, increased reliability, and
  commonality with the MD-11 fleet.

http://www.boeing.com/commercial/aeromagazine/aero_02/textonly/ps02txt.html
Just adding a little more info:

FAA Certifies New B757/767 Aftermarket Flight Deck
  Dreamliner-Inspired Large-Format Display System Enhances Situational Awareness

http://www.aero-news.net/index.cfm?do=main.textpost&id=c3201f75-7587-4438-a2b8-e35c3cb34759

This is what I was just about to answer with. It was a pretty significant leap - it lowered the crew from 3 (2 pilots + flight engineer) to 2, and went to a full glass cockpit. It seems like one of the best examples of this sort of work.

There's a couple of cases I know of to hand. UPS upgraded their 727 fleet with glass cockpits, there's also an STC for a full DC9 cockpit upgrade.

Vaslan developed an STC for a two man Boeing 727 cockpit on the re-engined B727-RE. This required automation of fuel management systems, hydraulics, electricals and pneumatic systems and repositioning these to the overhead P-5 panel. The pedastal was also extended rearwards.
There are a number of VIP B727s flying with all glass EFIS cockpit panels.
Usually a cockpit redesign will feature a suite of instrument products from one manufacturer for example like Rockwell-Collins, or Smiths etc and present it as an integrated platform.
I don't know who owns the STC currently but in theory if you wanted to the conversion could be carried anywhere out through a sub-contractor.


text:
Does the FAA or FSS check or authorise IFR flight plans?
There is an existing question about VFR flight plans the answers to which suggest that FSS dont check these and the main purpose of filing GA VFR flight plans is to aid subsequent S&R efforts.
You could therefore file a flight plan where some aspect is beyond the aircraft's capabilities (payload, range, altitude, GNSS, other equipment, etc).
How about IFR flight plans for chartered commercial flights for example.
The International Flight Plan form has a box labelled "ACCEPTED BY" but I assume this just indicates that the plan has been received and filed successfully, not that it has been checked for completeness, feasibility or safety or that it has passed some authorisation process.
For IFR flight plans, is there any FAA-mandated checking or authorisation performed by FSS or other quasi-official body at time of filing other than simplistic checking that something has been entered in mandatory fields?

In the US other reasons for filing VFR flight plans are: when exiting or entering the country (crossing the ADIZ), entering or exiting the DC ADIZ, and entering presidential TFRs.

FYI, when you file a flight plan ATC (Actually Lockheed-Martin first and they forward to ATC) does not know your payload, range, altitude capability.

The FAA's flight plan filing FAQ says that it's about formatting:

Q: Will an FPL be automatically rejected or is that a manual function?
A: ERAS automatically rejects an improperly formatted FPL. The Rejection (REJ) message usually includes information which identifies
  the error. The filer should correct the error and reenter the FPL.

That seems to be confirmed in this FAA ICAO Flight Planning Interface Reference Guide that goes into detail on computerized flight plan formats, filing etc. Section 3.7.2 lists all the possible reasons for the ERAS computer to return a REJ (rejected) message, and they're all to do with formatting or invalid values, e.g. airspeed can't be zero.
To me, that makes sense: no one knows the equipment or capabilities of an aircraft except the person (or organization) submitting the flight plan. Even if the FAA had a database of every aircraft in the world, what happens if your GPS unit burns out and you want to file IFR using only standard IFR equipment (VOR, ILS)? Or you want to fly at a reduced (or increased) cruise speed for some mechanical or performance testing reason? The FAA couldn't possibly know if your submitted values are correct.
I don't know (and couldn't find out) if there's any situation where ERAM can't generate a flight strip even though the flight plan is accepted as valid. If it does happen, I suppose that would be a sort of secondary check.
As an aside, I was at an EAA IMC Club meeting last week and we discussed the new ICAO flight plan format (new to the US, that is!). A couple of controllers were there, and they said that you have to be careful about what equipment you put in your flight plan in case you get assigned something beyond the pilot's capabilities. For example, a Cirrus is PBN-capable and if you input all the equipment correctly in the flight plan then you may get a complex SID rather than just departure vectors. If you aren't familiar and comfortable with the avionics then you might get yourself in trouble, so it would be better to file only basic avionics. That kind of decision isn't something the FAA could or should validate.

+1 for mentioning pilots level of confidence in using the advanced avionics.

It’s worth noting that the FAA will “accept” any route you file but may change it before you get your clearance, whereas many other countries will reject your flight plan unless you file a route they are willing to issue.

I do not know the answers to most of your question. I suspect that Pondlife is correct that none of the values are sanity-checked (e.g. filing FL300 in a Skylane, or filing Tango/Q-routes as /A) with the possible exception of looking for a proper equipment code if you file for RVSM airspace. Even that I'm doubtful of.
But there are "preferential routes" (prefroutes) defined for airport pairs in the Center's computer. These could be obvious: If you file direct from JFK to ORD you aren't going to get it; instead you'll get

JFK..COATE.Q436.EMMMA.WYNDE2.ORD

which is the preferred route in the NFDC database. But some routes are not nationally mandated and I don't know if there's any way to look them up; for example at my facility pilots who file direct to a certain airport will be routed over a particular VOR so as to keep them in Center's airspace and away from a busy approach control. These preferential routes will print out something like this on a flight strip:

+DEF FOOBR QUZ KXYZ+
KABC KXYZ

and the clearance controller will give you a full-route clearance using the route on the top line. Or they might only be a partial reroute, for example:

+DEF FOOBR+
KABC FOOBR QUZ KXYZ

and you would be cleared "direct DEF, direct FOOBR, then as filed."


text:
What measures were taken to keep Soviet airline pilots in the Soviet Union?
How did the Soviet Union keep airline pilots from leaving the country?
It seems like it would have been pretty easy to do since the pilots are already in the air. And I would guess at least some flew close to the borders.

Can you be more specific about what these pilots would be leaving for? Seems like Aeroflot has had flights to much of Europe throughout the Soviet era, and certainly does now.

We need @flyingfisch to elaborate on his question, but the way I interpret it, he's asking why, in the days of the cold war, did the aeroflot pilots not just fly to a western country and defect. Or not even fly to western European countries, but say to Poland, and then just keep going to, say, France. I think this is as much for History.SE than Aviation.SE.

I think this is an example of begging the question. You're assuming they would have wanted to defect. Besides, Aeroflot did fly international routes (including many in Western Europe), so the pilots could have defected if they wanted to. Being in a prestigious job, a member of a privileged social class and leaving their families behind would have been factors to consider, and in all likelihood it would have meant the end of their aviation careers. The lesson here is: do not just accept Western propaganda.

Why on earth would a pilot want to defect? How many serving pilots were sufficiently at odds with the regime to feel that uncomfortable in their lives and positions? Poets and playwrights with troublesome opinions, sure. Political figures on the losing side of internal struggles, of course. Pilots?!

For commercial flights, the USSR had a "Political Officer" (KGB agent) on the plane in much the same role as Air Marshals today, just the other direction - they kept the pilots from hijacking the aircraft. The system would have also insured that the flight crew's family were safely at home in Mother Russia when the pilot was abroad.
Military aircraft were kept at home by the simple method of small fuel tanks. The MIG-19 was once described as a plane that "goes nowhere, and does nothing, very quickly". Sure, they had decent range with external tanks, but a good number of Soviet-era fighters could realistically declare a fuel emergency right after takeoff.

Russian planes had smaller tanks because they were designed for defense. Bigger tanks are needed if you have a desire to attack far away countries. Please forget most cold war propaganda and look at the facts, and it will be clear that Russian planes served a different purpose than those of that other peace-loving nation which you use for comparison.

I'm sure there were many factors going into the airframe design. But you don't put tiny tanks into interceptors unless you have a reason to. And I used no other countries for comparison.

@PeterKämpf preventing defection was a factor, even if not an overriding one. A lot of their designs could have been a lot more flexible with larger tanks. As is, they often designed explicit short and long range aircraft to do essentially the same task, with the long range aircraft being assigned only to regions far from the borders.

@PeterKämpf Switzerland?

In the Eighties, a Soviet MiG-23 had engine trouble and the pilot ejected. Somehow the engine recovered, and the plane flew westward, unmanned, until it crashed in Belgium (http://theaviationist.com/2012/10/03/mig23-belgium/). Seems their tanks were not so small, after all. There had been plenty of opportunity to defect. Please, again, forget the propaganda and accept the facts. There were very few pilots who defected. Viktor Belenko was an exceptional case. And consider how much bounty the Taiwanese had to offer for Chinese pilots to defect.

@PeterKämpf if anything, that story confirms the small fuel tanks. I just used SkyVector to measure out Kolobrzeg to Soesterberg; it's a little over 700km. Depending on how much fuel had been expended already, that's not a particularly long range. Keep in mind that the combat radius is how far an aircraft can go, loiter for x minutes, and return to base; most Soviet aircraft were very low on loiter time, which seems odd for a defensive emphasis.

In what context would you consider loiter as part of a defense mission??? MiGs were interceptors, directed by ground control to airborne targets picked up by long-range radar. Making them any bigger would have cost more. The design was really well adapted for the intended mission, and the tanks were big enough. Loiter is what you do if you attack targets of opportunity - now that's NOT a defensive task.

@PeterKämpf My grandmother escaped from the Russians during WWII, and my Great-Uncle fought in the 1956 Hungarian revolution. The things Americans were told about the Russians was not propoganda. If anything, the US should have publicized Soviet atrocities more. Also, I do not necessarily think the US was a perfect supporter of peace either. We promised to support the Hungarian revolution, and then we backed out of our promise. Americans hardly even knew what was going on, because our media wouldn't cover it. And the Gulag and Secret Police were no joke. Life in the USSR was bad. Period.

@flyingfish: War != Peace. Big difference.

This is not really a very satisfactory answer; it reads like something from a rather unsophisticated western propaganda handout ca. 1986. Some of it simply false (e.g. the inference drawn re "Political Officers"). The rest just isn't borne out by the evidence, and is at odds with actual facts.

Civilian pilots had a quite comfortable life. Flying high-tech gear has an attraction in itself, and the propaganda did what it could to strengthen patriotic spirits. There were not many reasons to defect if you did not mind the nonsense in the papers but appreciated to be part of a privileged class. And everybody knew that defection would have dire consequences for all relatives left behind.
The same is true for military pilots, and on top the Russian air defense was organized quite differently from NATO's, thus military pilots flew almost by remote control. This went as far as using radios which had only a dozen of pre-set frequencies. The pilots did not know the frequency, they just pushed the button with the number they were told by ground control.

And after the defection, how they would make a living? Driving a cab?

Yes, why not? Most likely not as pilots. Or do you know an example?

My comment was explanation what kept pilots from defecting. That after defection, they would not be able to fly. So (IMHO) your answer is more correct. What kept them "inside" wan not fear of KBG officer's gun, but fear of how to make living after the defection, losing the ability to fly, and reprisal against their families if they had any.

@PeterMasiar Eh, if conditions were bad enough, the ability to fly may not have been a good enough incentive. It wasn't for some pilots, at least. Example, Another example

@flyingfisch Wikipedia has plenty more examples.

@DavidRicherby Ah, nice, all lined up by country. So the point stands: Some pilots did want to get out of the USSR.

I think so, too. Furthermore the following articel includes some interessting remarks, start reading in the middle if you cannot spend a complete hour (but I would recommend it):  http://foxtrotalpha.jalopnik.com/how-to-win-in-a-dogfight-stories-from-a-pilot-who-flew-1682723379 "What was the MiG-29 Fulcrum like to fly? Did it live up to the fear and Cold War hype?" Strongly depends on ground control + small combat radius, 150 nautical miles sound less to me.

+1 People don't flee countries they flee harsh lifes while one can say thousands flee from Cuba I can point millions flee from Mexico

The premise of the question, that pilots in the Soviet Union needed somehow to be "kept in" as if they wanted to leave, is simply false.
Also simply false is the inference in drawn in the the answer (currently accepted as correct!) about the role of "Political Officers".
Life in the USSR was frankly horrendous for many people: certain ethnic minorities, those who belonged to national or political groups that had fought and lost battles with the ruling classes, dissidents - but funnily enough, these people didn't often get to become airline pilots (or airline staff, or diplomats, or functionaries who got to travel across international borders as part of their work).
People who got to travel in those ways were already part of a trusted, privileged elite.
In a few words: what kept pilots from defecting from the USSR was that, on the whole, they didn't have a reason to want to.
Specious explanations don't need to be invented.
The people who wanted to leave because they were suffering dreadful privations and restrictions at the hands of the Soviet state weren't allowed to leave their towns, have telephones in their apartments or own typewriters - they idea that they might be allowed to pilot airliners is just a joke.
The notion of that airline pilots might be seeking to defect as a matter of course is honestly risible, however nicely it might harmonise with a certain Cold War narrative.
You can see how bogus the reasoning is: if the "Political Officers" were there to prevent defection, do you imagine they had one assigned 24 hours a day to each member of an international flight's crew on their overnight stays outside the USSR? It's nonsense.

The system would have also insured that the flight crew's family were safely at home in Mother Russia when the pilot was abroad

Sure, the families of dissidents and refuseniks were effectively deployed as leverage. But people like pilots?! It's just not the case. For the most part, Russians posted abroad were posted with their families when appropriate, just like everyone else.
As I said, life in the Soviet Union could be quite ghastly if you were on the wrong side of things, but there's really no need to recapitulate stale old Cold War propaganda to try to paint a picture that is worse than the reality was.

"Russians posted abroad were posted with their families" - this doesn't exactly apply to the pilots since they were not "posted abroad", but came back in a few days. So their families became natural hostages, whether this was intended or not.


text:
What’s the difference between “Bandit” and “Bogey”
When I was watching Top Gun Maverick, the EWAC called the 2 incoming SU-57s “bandits”, but when Maverick says it he says “bogies incoming“. (Correct me if that isn’t what they said).
So why don’t they just call them "bandits" and not "bogies".

According to the Multiservice Tactical Brevity Codes
a Bandit is

An aircraft identified as enemy, in accordance with theater ID criteria. The term does not necessarily imply direction or authority to engage.

and a Bogey is

A radar or visual air contact whose identity is unknown.

The RAF had a much smaller set of codes but the meaning is fairly consistant with the American/NATO codes above

Bandit – identified enemy aircraft.
Bogey – unidentified (possibly unfriendly) aircraft.

I'd add comment that in USAF, (at least 40 years ago), we also made a distinction in calling out visual acquisition of aircraft. If you acquired an known enemy, we said "TALLY". If you did not have the enemy aircraft, "NO JOY". for friendly aircraft we said "VISUAL" and "BLIND" e.g., "LOCUST TWO TALLY 2 BANDITS 10 O'CLOCK HIGH RIGHT TO LEFT 2 MILES"

@CharlesBretana, there’s a call for having them on the fighter’s AA radar too isn’t there?

Yes, The call was the word "CONTACT", as in "RUCKUS 21. CONTACT, 270 12 miles, ANGELS TWENTY-FOUR... " As I recall, we also had code-words to communicate the information from our electronic IFF (Identification Friend or Foe) systems, but I have forgotten what those words were.

Traditionally, a 'bandit' is identified bad guy, whereas a 'bogey' is unidentified - could be bad guy, could be one of ours.

Or could be civilian, or 3rd party military on an unrelated mission, not part of whatever conflict you're worried about.


text:
In a jet engine, what is the significance of the stagnation pressure/temperature?
I'm reading a paper on jet engines that repeatedly mentions the stagnation pressure and temperature. What does this mean? Is it the point where the jet engine stalls in performance/efficiency/thrust, etc?
I'm a bit confused. 99% of the information on stagnation pressure is the static pressure, or the about stagnation point, or pressure where fluid velocity is zero.

Hi @itisyeetimetoday - does this https://engineering.stackexchange.com/a/15617 answer your question?

What paper?  Can you post a reference/citation so we can read it and get the context of the statement?

Image source
Stagnation pressure is used as a synonym for total pressure. An object in airflow experiences pressure from the flow = dynamic pressure, indeed for incompressible flow proportional to the velocity squared.
In the pic above, on the right hand side, is an indication of the Stagnation Point. This is where the air streaming in does not flow around the cylinder but is stopped by the body contour. The flow stagnates, and all inflowing dynamic air pressure is converted into static pressure at this point.
Which is called the stagnation pressure.

The analytical formula for the stagnation pressure $p_{st}$ is :
$$p_{st} = p_{\infty} + \frac{1}{2} \rho V^2$$
with $p_∞$ static pressure, $\rho$ = air density, $V$ = air speed for incompressible flow.
The point where the fluid is at rest is the point where stagnation pressure = static pressure ($p_{\infty} = p_{st}$), because the kinetic energy of the fluid is 0.
For compressible flows you can calculate the ratio of Stagnation/Static pressure with the formula :
$$\frac{p_{st}}{p_∞} = {\left( 1 + \frac{\gamma - 1}{2}M^2\right)}^{\frac{\gamma}{\gamma - 1}} $$ , simply by replacing Mach=0 then you can see that the stagnation pressure = static.
Try understanding how pitot measurement for pressure works and try studying Anderson for Fundamental Aerodynamics.
Hope that helps

Have converted the formulae into mathjax, there's a tutorial here.


text:
Did the F-16 have an AoA limiter since the very first variant?
Did the F-16 have an AoA limiter since the very first variant or was it added later?

The F16 was designed from the outset to be aerodynamically unstable with the computer keeping it within the constraints of the current flight envelope - including restricting the AoA to safe limits. In that sense, yes, it had an AoA limiter from the first production versions onwards.